The present invention relates to the general field of measuring temperature in the primary stream of a two-spool bypass turbojet, this measurement being performed at the inlet to the high-pressure compressor.
In a two-spool bypass turbojet, the measurement of the temperature of the gas stream flowing in the primary flow passage at the inlet of its high-pressure compressor (this temperature is also referred to as the “temperature T25”) is used in numerous relationships for regulating the turbojet. The measurement of the temperature T25 appears in particular in the relationship for determining the positions of the various variable-geometry parts of the turbojet.
It is known to measure the temperature T25 by means of a temperature probe that is placed directly in the primary stream flow passage at the inlet to the high-pressure compressor. Usually, such probes comprise a casting fitted with an inertial separator for protecting the sensitive element of the probe against moisture, water, ice, sand, and other foreign bodies. The casting may also include a heater resistance that is activated to prevent the formation of ice that might otherwise obstruct the inlet of the probe and that could present a mass that might damage the blades downstream.
That type of probe with an inertial separator presents numerous drawbacks. In particular the casting is complex to fabricate, thereby making the cost of the probe high. Furthermore, the presence of the probe in the primary stream flow passage creates a wake that disturbs said flow as it penetrates into the high-pressure compressor. Furthermore, the de-icing function of the probe requires an external electrical power supply and a switch relay in the electronic computer of the turbojet, and also requires software to correct the measurement error that results from the heating of the casting. Finally, the probe must withstand aerodynamic stresses at high frequencies.